U.S. patent application number 16/863297 was filed with the patent office on 2020-08-27 for resin composition for acoustic matching layer, cured product, acoustic matching sheet, acoustic probe, acoustic measuring appara.
This patent application is currently assigned to FUJIFILM Corporation. The applicant listed for this patent is FUJIFILM Corporation. Invention is credited to Kazushi Furukawa, Kazuhiro Hamada, Yoshihiro Nakai.
Application Number | 20200270448 16/863297 |
Document ID | / |
Family ID | 1000004870583 |
Filed Date | 2020-08-27 |
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United States Patent
Application |
20200270448 |
Kind Code |
A1 |
Hamada; Kazuhiro ; et
al. |
August 27, 2020 |
RESIN COMPOSITION FOR ACOUSTIC MATCHING LAYER, CURED PRODUCT,
ACOUSTIC MATCHING SHEET, ACOUSTIC PROBE, ACOUSTIC MEASURING
APPARATUS, METHOD FOR PRODUCING ACOUSTIC PROBE, AND ACOUSTIC
MATCHING LAYER MATERIAL SET
Abstract
Provided is a resin composition for an acoustic matching layer,
the resin composition including an epoxy resin (A), a specific
polyamine compound (B), and metal particles (C). The epoxy resin
(A) includes at least one epoxy resin selected from the group
consisting of bisphenol A epoxy resins, bisphenol F epoxy resins,
and phenol novolac epoxy resins. Also provided are a cured product
formed of the composition, an acoustic matching sheet, an acoustic
probe, an acoustic measuring apparatus, a method for producing an
acoustic probe, and an acoustic matching layer material set.
Inventors: |
Hamada; Kazuhiro; (Kanagawa,
JP) ; Furukawa; Kazushi; (Kanagawa, JP) ;
Nakai; Yoshihiro; (Kanagawa, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
FUJIFILM Corporation |
Tokyo |
|
JP |
|
|
Assignee: |
FUJIFILM Corporation
Tokyo
JP
|
Family ID: |
1000004870583 |
Appl. No.: |
16/863297 |
Filed: |
April 30, 2020 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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PCT/JP2018/040440 |
Oct 31, 2018 |
|
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16863297 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C08K 2003/0893 20130101;
C08K 2003/0862 20130101; C08K 2003/0856 20130101; C08K 2003/0806
20130101; G10K 11/18 20130101; C08L 63/00 20130101; C08K 2003/0887
20130101; C08K 5/17 20130101; G01N 29/2437 20130101; G10K 11/36
20130101; C08G 59/5033 20130101; C08K 2003/085 20130101 |
International
Class: |
C08L 63/00 20060101
C08L063/00; G01N 29/24 20060101 G01N029/24; G10K 11/36 20060101
G10K011/36; G10K 11/18 20060101 G10K011/18; C08G 59/50 20060101
C08G059/50 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 1, 2017 |
JP |
2017-212209 |
Claims
1. A resin composition for an acoustic matching layer, comprising:
an epoxy resin (A); a polyamine compound (B1) represented by
general formula (I) below; and metal particles (C), wherein the
epoxy resin (A) includes at least one epoxy resin selected from the
group consisting of bisphenol A epoxy resins, bisphenol F epoxy
resins, and phenol novolac epoxy resins: L NH.sub.2).sub.n general
formula (I) where, in general formula (I), n represents an integer
of 2 to 20, and L represents an n-valent aliphatic hydrocarbon
group having an aliphatic hydrocarbon chain into which at least one
oxygen atom is incorporated or an n-valent group having an aromatic
ring and an aliphatic hydrocarbon group having at least one oxygen
atom.
2. The resin composition for an acoustic matching layer according
to claim 1, wherein the polyamine compound (B1) is at least one
polyamine compound represented by general formula (II), (III), or
(IV) below: ##STR00011## where, in general formula (II), s
represents an integer of 1 to 100, n1 represents an integer of 2 to
20, L.sup.1 represents an n1-valent aliphatic hydrocarbon group
having 1 to 20 carbon atoms or an n1-valent aromatic hydrocarbon
group having 6 to 20 carbon atoms, and L.sup.2 represents an
aliphatic hydrocarbon chain having 2 to 6 carbon atoms, in general
formula (III), t represents an integer of 1 to 100, n2 represents
an integer of 1 to 19, L.sup.3 represents an (n2+1)-valent
aliphatic hydrocarbon group having 1 to 20 carbon atoms or an
(n2+1)-valent aromatic hydrocarbon group having 6 to 20 carbon
atoms, and L.sup.4 represents an aliphatic hydrocarbon chain having
2 to 6 carbon atoms, and in general formula (IV), u represents an
integer of 1 to 100, n3 and n4 each represent an integer of 1 or
more, a sum of n3 and n4 is 20 or less, L.sup.5 represents an
(n3+1)-valent aliphatic hydrocarbon group having 1 to 20 carbon
atoms or an (n3+1)-valent aromatic hydrocarbon group having 6 to 20
carbon atoms, L.sup.6 represents an (n4+1)-valent aliphatic
hydrocarbon group having 1 to 20 carbon atoms or an (n4+1)-valent
aromatic hydrocarbon group having 6 to 20 carbon atoms, and L.sup.7
represents an aliphatic hydrocarbon chain having 2 to 6 carbon
atoms.
3. The resin composition for an acoustic matching layer according
to claim 1, further comprising a polyamine compound (B2), wherein
the polyamine compound (B2) is a polyamine compound not having an
oxygen atom as a constituent atom.
4. The resin composition for an acoustic matching layer according
to claim 3, wherein the polyamine compound (B2) is a polyamine
compound having an alicyclic ring.
5. The resin composition for an acoustic matching layer according
to claim 1, wherein the metal particles (C) include a metal atom in
groups 4 to 12.
6. The resin composition for an acoustic matching layer according
to claim 1, wherein the metal particles (C) include at least one of
Zn, Au, Ag, Zr, W, Ta, Fe, Cu, Ni, Pt, or Mo.
7. The resin composition for an acoustic matching layer according
to claim 1, wherein an equivalent ratio of contents of the epoxy
resin (A) and the polyamine compound (B1) satisfies polyamine
compound (B1)/epoxy resin (A)=0.5/1 to 1/0.5.
8. The resin composition for an acoustic matching layer according
to claim 3, wherein an equivalent ratio of contents of the epoxy
resin (A) and the polyamine compound (B2) satisfies polyamine
compound (B2)/epoxy resin (A) 0.9.
9. A cured product formed by curing the resin composition for an
acoustic matching layer according to claim 1.
10. An acoustic matching sheet comprising the cured product
according to claim 9.
11. An acoustic probe comprising the acoustic matching sheet
according to claim 10 as an acoustic matching layer.
12. An acoustic measuring apparatus comprising the acoustic probe
according to claim 11.
13. The acoustic measuring apparatus according to claim 12, wherein
the acoustic measuring apparatus is an ultrasound diagnostic
apparatus.
14. A method for producing an acoustic probe, comprising forming an
acoustic matching layer by using the resin composition for an
acoustic matching layer according to claim 1.
15. An acoustic matching layer material set comprising: a base
resin made of a resin composition including metal particles (C) and
at least one epoxy resin (A) selected from the group consisting of
bisphenol A epoxy resins, bisphenol F epoxy resins, and phenol
novolac epoxy resins; and a curing agent including at least one
polyamine compound (B1) represented by general formula (I) below: L
NH.sub.2).sub.n general formula (I) where, in general formula (I),
n represents an integer of 2 to 20, and L represents an n-valent
aliphatic hydrocarbon group having an aliphatic hydrocarbon chain
into which at least one oxygen atom is incorporated or an n-valent
group having an aromatic ring and an aliphatic hydrocarbon group
having at least one oxygen atom.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a Continuation of PCT International
Application No. PCT/JP2018/040440 filed on Oct. 31, 2018, which
claims priority under 35 U.S.C. .sctn. 119 (a) to Japanese Patent
Application No. 2017-212209 filed in Japan on Nov. 1, 2017. Each of
the above applications is hereby expressly incorporated by
reference, in its entirety, into the present application.
BACKGROUND OF THE INVENTION
1. Field of the Invention
[0002] The present invention relates to a resin composition for an
acoustic matching layer, a cured product, an acoustic matching
sheet, an acoustic probe, an acoustic measuring apparatus, a method
for producing an acoustic probe, and an acoustic matching layer
material set.
2. Description of the Related Art
[0003] An acoustic measuring apparatus includes an acoustic probe
that irradiates a subject such as a living body with acoustic waves
and receives reflected waves (echoes) therefrom to output a signal.
The reflected waves received by the acoustic probe are converted
into an electrical signal. The electrical signal is displayed as an
image. Therefore, using an acoustic probe allows the inside of a
subject to be visualized and observed.
[0004] Appropriate acoustic waves such as ultrasonic waves or
photoacoustic waves are selected depending on the subject and the
measurement conditions.
[0005] For example, an ultrasound diagnostic apparatus, which is an
acoustic measuring apparatus, transmits ultrasonic waves toward the
inside of a subject, receives ultrasonic waves reflected by a
tissue inside the subject, and displays an image.
[0006] A photoacoustic measuring apparatus receives acoustic waves
radiated from inside a subject due to a photoacoustic effect and
displays an image. The photoacoustic effect is a phenomenon in
which, when a subject is irradiated with pulses of electromagnetic
waves such as visible light, near-infrared light, or microwaves,
the subject absorbs the electromagnetic waves to cause heat
generation and thermal expansion, whereby acoustic waves
(typically, ultrasonic waves) are generated.
[0007] The acoustic measuring apparatus transmits and receives
acoustic waves to and from a subject, and thus the acoustic probe
is required to provide acoustic impedance matching to a subject. To
meet this requirement, the acoustic probe includes an acoustic
matching layer. This will be described with reference to an
ultrasound diagnostic apparatus search unit (also referred to as an
ultrasound probe), which is an acoustic probe.
[0008] The ultrasound probe includes a piezoelectric element for
transmitting and receiving ultrasonic waves and an acoustic lens
configured to be in contact with a living body, and an acoustic
matching layer is disposed between the piezoelectric element and
the acoustic lens. Ultrasonic waves oscillated from the
piezoelectric element pass through the acoustic matching layer and
further through the acoustic lens to enter a living body. In
general, there is a difference in acoustic impedance
(density.times.sound velocity) between the acoustic lens and a
living body. When this difference is large, ultrasonic waves are
likely to be reflected by a living body surface, and the efficiency
of entrance of ultrasonic waves into a living body is low. Thus,
the acoustic lens is required to have acoustic impedance
characteristics close to those of a living body.
[0009] On the other hand, the difference in acoustic impedance
between the piezoelectric element and a living body is generally
large. Accordingly, the difference in acoustic impedance between
the piezoelectric element and the acoustic lens is generally large.
Therefore, when the piezoelectric element and the acoustic lens are
stacked on top of each other, ultrasonic waves emitted from the
piezoelectric element are reflected by a surface of the acoustic
lens, and the efficiency of entrance of ultrasonic waves into a
living body is low. To reduce such reflection of ultrasonic waves,
the above acoustic matching layer is disposed between the
piezoelectric element and the acoustic lens. The acoustic impedance
of the acoustic matching layer is between the acoustic impedance of
a living body or the acoustic lens and the acoustic impedance of
the piezoelectric element, which increases the efficiency of
propagation of ultrasonic waves from the piezoelectric element to a
living body. It is also known that when the acoustic matching layer
has a multilayer structure with a gradient in acoustic impedance
from the piezoelectric element side toward the acoustic lens side,
the efficiency of propagation of ultrasonic waves is further
increased.
[0010] The acoustic probe is required to have sufficient mechanical
strength in addition to the acoustic characteristics described
above. The acoustic matching layer is often used in the form of a
thin film (e.g., several hundred micrometers), and cutting
processing is performed to achieve a desired thickness. Thus, the
acoustic matching layer is required to have mechanical strength
sufficient to withstand the cutting processing. The acoustic probe
is used while being rubbed, sometimes pressed, against a living
body, and thus the mechanical strength directly affects the product
life of the acoustic probe.
[0011] It is known that epoxy resins, polyimide resins, silicone
resins, polyolefin resins, cycloolefin resins, polyester resins,
polyvinyl butyral resins, and other resins are used as constituent
materials of the acoustic matching layer (e.g.,
JP2009-296055A).
SUMMARY OF THE INVENTION
[0012] For the acoustic matching layer of the acoustic probe, a
material is employed that has an acoustic impedance adjustable to
be at a desired level between an acoustic impedance of the
piezoelectric element and an acoustic impedance of a living body.
The present inventors have studied and found that the acoustic
matching layer disclosed in JP2009-296055A may have poor mechanical
strength and variation in intralayer acoustic characteristics.
[0013] Thus, an object of the present invention is to provide a
resin composition for an acoustic matching layer and an acoustic
matching layer material set suitable for preparation of the
composition. From the resin composition, an acoustic matching layer
having high mechanical strength and little variation in intralayer
acoustic characteristics can be formed.
[0014] Another object of the present invention is to provide an
acoustic matching sheet having high mechanical strength and little
variation in intrasheet acoustic characteristics and a cured
product used therefor.
[0015] Still another object of the present invention is to provide
an acoustic probe having high mechanical strength and little
variation in acoustic characteristics and an acoustic measuring
apparatus including the acoustic probe.
[0016] Yet still another object of the present invention is to
provide a method for producing an acoustic probe having high
mechanical strength and little variation in acoustic
characteristics.
[0017] To achieve the above objects, the present inventors
conducted intensive studies and found that a sheet formed by using
a composition for forming an acoustic matching layer, the
composition including metal particles, a specific epoxy resin, and
a specific polyamine compound serving as a curing agent for the
epoxy resin, has high mechanical strength and reduced variation in
intralayer acoustic characteristics. The present invention has been
completed by further conducting studies based on this finding.
[0018] Thus, the above objects of the present invention have been
achieved by the following means.
<1> A resin composition for an acoustic matching layer
includes an epoxy resin (A), a polyamine compound (B1) represented
by general formula (I) below, and metal particles (C).
[0019] The epoxy resin (A) includes at least one epoxy resin
selected from the group consisting of bisphenol A epoxy resins,
bisphenol F epoxy resins, and phenol novolac epoxy resins.
L NH.sub.2).sub.n General formula (I)
[0020] In general formula (I), n represents an integer of 2 to 20.
L represents an n-valent aliphatic hydrocarbon group having an
aliphatic hydrocarbon chain into which at least one oxygen atom is
incorporated or an n-valent group having an aromatic ring and an
aliphatic hydrocarbon group having at least one oxygen atom.
<2> In the resin composition for an acoustic matching layer
according to <1>, the polyamine compound (B1) is at least one
polyamine compound represented by general formula (II), (III), or
(IV) below.
##STR00001##
[0021] In general formula (II), s represents an integer of 1 to
100, and n1 represents an integer of 2 to 20. L.sup.1 represents an
n1-valent aliphatic hydrocarbon group having 1 to 20 carbon atoms
or an n1-valent aromatic hydrocarbon group having 6 to 20 carbon
atoms, and L.sup.2 represents an aliphatic hydrocarbon chain having
2 to 6 carbon atoms.
[0022] In general formula (III), t represents an integer of 1 to
100, and n2 represents an integer of 1 to 19. L.sup.3 represents an
(n2+1)-valent aliphatic hydrocarbon group having 1 to 20 carbon
atoms or an (n2+1)-valent aromatic hydrocarbon group having 6 to 20
carbon atoms, and L.sup.4 represents an aliphatic hydrocarbon chain
having 2 to 6 carbon atoms.
[0023] In general formula (IV), u represents an integer of 1 to
100, n3 and n4 each represent an integer of 1 or more, and the sum
of n3 and n4 is 20 or less. L.sup.5 represents an (n3+1)-valent
aliphatic hydrocarbon group having 1 to 20 carbon atoms or an
(n3+1)-valent aromatic hydrocarbon group having 6 to 20 carbon
atoms. L.sup.6 represents an (n4+1)-valent aliphatic hydrocarbon
group having 1 to 20 carbon atoms or an (n4+1)-valent aromatic
hydrocarbon group having 6 to 20 carbon atoms. L.sup.7 represents
an aliphatic hydrocarbon chain having 2 to 6 carbon atoms.
<3> The resin composition for an acoustic matching layer
according to <1> or <2> further includes a polyamine
compound (B2), and the polyamine compound (B2) is a polyamine
compound not having an oxygen atom as a constituent atom. <4>
In the resin composition for an acoustic matching layer according
to <3>, the polyamine compound (B2) is a polyamine compound
having an alicyclic ring. <5> In the resin composition for an
acoustic matching layer according to any one of <1> to
<4>, the metal particles (C) include a metal atom in groups 4
to 12. <6> In the resin composition for an acoustic matching
layer according to any one of <1> to <5>, the metal
particles (C) include at least one of Zn, Au, Ag, Zr, W, Ta, Fe,
Cu, Ni, Pt, or Mo. <7> In the resin composition for an
acoustic matching layer according to any one of <1> to
<6>, the equivalent ratio of contents of the epoxy resin (A)
and the polyamine compound (B1) satisfies polyamine compound
(B1)/epoxy resin (A)=0.5/1 to 1/0.5. <8> In the resin
composition for an acoustic matching layer according to <3>
or <4>, the equivalent ratio of contents of the epoxy resin
(A) and the polyamine compound (B2) satisfies polyamine compound
(B2)/epoxy resin (A) 0.9. <9> A cured product is formed by
curing the resin composition for an acoustic matching layer
according to any one of <1> to <8>. <10> An
acoustic matching sheet includes the cured product according to
<9>. <11> An acoustic probe includes the acoustic
matching sheet according to <10> as an acoustic matching
layer. <12> An acoustic measuring apparatus includes the
acoustic probe according to <11>. <13> In the acoustic
measuring apparatus according to <12>, the acoustic measuring
apparatus is an ultrasound diagnostic apparatus. <14> A
method for producing an acoustic probe includes forming an acoustic
matching layer by using the resin composition for an acoustic
matching layer according to any one of <1> to <8>.
<15> An acoustic matching layer material set includes a base
resin made of a resin composition including metal particles (C) and
at least one epoxy resin (A) selected from the group consisting of
bisphenol A epoxy resins, bisphenol F epoxy resins, and phenol
novolac epoxy resins, and a curing agent including at least one
polyamine compound (B1) represented by general formula (I)
below.
L NH.sub.2).sub.n General formula (I)
[0024] In general formula (I), n represents an integer of 2 to 20.
L represents an n-valent aliphatic hydrocarbon group having an
aliphatic hydrocarbon chain into which at least one oxygen atom is
incorporated or an n-valent group having an aromatic ring and an
aliphatic hydrocarbon group having at least one oxygen atom.
[0025] In the description of the present invention, the expression
"to" is meant to include the numerical values before and after "to"
as the lower and upper limits.
[0026] In the description of the present invention, when the number
of carbon atoms of a group is specified, the number of carbon atoms
means the number of carbon atoms of the whole group. That is, when
the group further has a substituent, the number of carbon atoms
means the number of carbon atoms of the whole including the
substituent.
[0027] In the description of the present invention, when there are
a plurality of substituents, a plurality of linking groups, or the
like represented by a particular symbol (hereinafter referred to as
"substituents or the like") or when a plurality of substituents or
the like are simultaneously or alternatively specified, the
substituents or the like may be the same or different. Furthermore,
even if not specifically stated, when a plurality of substituents
or the like are adjacent to each other, they may be linked or fused
to each other to form a ring.
[0028] The resin composition for an acoustic matching layer and the
acoustic matching layer material set according to the present
invention, when formed or processed into a desired sheet shape, can
provide an acoustic matching sheet having high mechanical strength
and little variation in intrasheet acoustic characteristics.
[0029] The acoustic matching sheet according to the present
invention has high mechanical strength and little variation in
intrasheet acoustic characteristics. The cured product according to
the present invention is suitable as a constituent material of the
acoustic matching layer according to the present invention.
[0030] The acoustic probe according to the present invention and
the acoustic measuring apparatus including the acoustic probe each
have high mechanical strength and little variation in acoustic
characteristics.
[0031] The method for producing an acoustic probe according to the
present invention can provide an acoustic probe having high
mechanical strength and little variation in acoustic
characteristics.
BRIEF DESCRIPTION OF THE DRAWINGS
[0032] FIG. 1 is a perspective view of an example of a convex
ultrasound probe, which is one aspect of an acoustic probe.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Resin Composition for Acoustic Matching Layer
[0033] A resin composition for an acoustic matching layer according
to the present invention (hereinafter also referred to simply as "a
composition according to the present invention") includes an epoxy
resin (A), a polyamine compound (B1), and metal particles (C). The
epoxy resin (A) and the polyamine compound (B1) included in the
composition according to the present invention fill gaps between
the metal particles (C) and function as dispersion media for the
metal particles (C).
[0034] Since the composition according to the present invention has
the above configuration, an acoustic matching sheet formed from the
composition has high mechanical strength and little variation in
intrasheet acoustic characteristics. Although not clear, the
reasons for this are presumably as follows.
[0035] In the composition according to the present invention, the
polyamine compound (B1) has an aliphatic hydrocarbon group having
at least one oxygen atom. Probably, the aliphatic hydrocarbon group
interacts with the metal particles (C) to stabilize the state of
dispersion of the metal particles (C) in the composition, whereby
the metal particles (C) are very evenly distributed in an acoustic
matching sheet.
[0036] When a polyamine compound not having an aliphatic
hydrocarbon group having at least one oxygen atom is used alone,
the rate of cure of the epoxy resin (A) in the presence of the
epoxy resin (A) and the metal particles (C) is often considerably
high or considerably low. When the rate of cure is considerably
high, the epoxy resin (A) cures before the metal particles (C) are
dispersed. On the other hand, when the rate of cure is considerably
low, the epoxy resin (A) cures after the metal particles (C) sink.
Thus, when a polyamine compound not having an aliphatic hydrocarbon
group having at least one oxygen atom is used alone, a uniform
sheet cannot be formed, leading to variation in acoustic
characteristics. By contrast, the polyamine compound (B1) has
characteristics between the above characteristics (adjusts the rate
of cure) in the presence of the epoxy resin (A) and the metal
particles (C) and thus allows the epoxy resin (A) to cure with the
metal particles (C) being moderately dispersed. The composition
according to the present invention produces both the above effects
probably because of a combination of the dispersion stability of
the metal particles (C) in the composition and the moderate rate of
cure in forming a sheet.
Epoxy Resin (A)
[0037] The epoxy resin (A) used in the present invention includes
at least one epoxy resin selected from the group consisting of
bisphenol A epoxy resins, bisphenol F epoxy resins, and phenol
novolac epoxy resins.
[0038] The bisphenol A epoxy resin used in the present invention is
not particularly limited and may be any bisphenol A epoxy resin
commonly used as a base resin of an epoxy adhesive. Specific
examples of preferred bisphenol A epoxy resins include bisphenol A
diglycidyl ethers (jER825, jER828, and jER834 (trade names),
manufactured by Mitsubishi Chemical Corporation) and bisphenol A
propoxylate diglycidyl ethers (manufactured by Sigma-Aldrich).
[0039] The bisphenol F epoxy resin used in the present invention is
not particularly limited and may be any bisphenol F epoxy resin
commonly used as a base resin of an epoxy adhesive. Specific
examples of preferred bisphenol F epoxy resins include bisphenol F
diglycidyl ethers (trade name: EPICLON830, manufactured by DIC
Corporation) and 4,4'-methylenebis(N,N-diglycidylaniline).
[0040] The phenol novolac epoxy resin used in the present invention
is not particularly limited and may be any phenol novolac epoxy
resin commonly used as a base resin of an epoxy adhesive. Such a
phenol novolac epoxy resin is marketed, for example, by
Sigma-Aldrich under the product number 406775.
[0041] The epoxy resin (A) may be composed of at least one of the
above epoxy resins or may include, in addition to at least one of
the above epoxy resins, another epoxy resin (e.g., an aliphatic
epoxy resin) as long as the effects of the present invention are
not impaired. The content of the above three types of epoxy resins
(the total content of a bisphenol A epoxy resin, a bisphenol F
epoxy resin, and a phenol novolac epoxy resin) in the epoxy resin
(A) is preferably 80 mass % or more, more preferably 90 mass % or
more.
Polyamine Compound (B1)
[0042] The polyamine compound (B1) used in the present invention is
a curing component that acts on the epoxy resin (A) to cure it and
is represented by general formula (I) below.
L NH.sub.2).sub.n General formula (I)
[0043] In general formula (I), n represents an integer of 2 to 20
(preferably 3 to 20). L represents an n-valent aliphatic
hydrocarbon group having an aliphatic hydrocarbon chain into which
at least one oxygen atom is incorporated or an n-valent group
having an aromatic ring and an aliphatic hydrocarbon group having
at least one oxygen atom.
[0044] The polyamine compound (B1) is preferably at least one
polyamine compound represented by general formula (II), (III), or
(IV) below. This is because the dispersibility of the metal
particles (C) can be further increased, and the rate of cure can be
more readily adjusted to a desired rate not too fast and not too
slow.
##STR00002##
[0045] In general formula (II), s represents an integer of 1 to
100, and n1 represents an integer of 2 to 20. L.sup.1 represents an
n1-valent aliphatic hydrocarbon group having 1 to 20 carbon atoms
or an n1-valent aromatic hydrocarbon group having 6 to 20 carbon
atoms, and L.sup.2 represents an aliphatic hydrocarbon chain having
2 to 6 carbon atoms.
[0046] The above aliphatic hydrocarbon groups and aliphatic
hydrocarbon chains may be linear or branched.
[0047] To provide an acoustic matching layer with further improved
breaking energy and further reduced variation in acoustic
characteristics, s is preferably an integer of 1 to 50, more
preferably an integer of 2 to 20.
[0048] n1 is preferably an integer of 1 to 15, more preferably an
integer of 2 to 6, still more preferably 3 or 4.
[0049] The above aliphatic hydrocarbon group represented by L.sup.1
is preferably an n1-valent aliphatic hydrocarbon group having 2 to
15 carbon atoms, more preferably an n1-valent aliphatic hydrocarbon
group having 3 to 10 carbon atoms, still more preferably an
n1-valent aliphatic hydrocarbon group having 5 or 6 carbon
atoms.
[0050] The above aromatic hydrocarbon group represented by L.sup.1
is preferably an n1-valent aromatic hydrocarbon group having 6 to
15 carbon atoms, more preferably an n1-valent aromatic hydrocarbon
group having 6 to 10 carbon atoms, still more preferably n1-valent
benzene.
[0051] L.sup.2 is more preferably an aliphatic hydrocarbon chain
having 2 to 4 carbon atoms, still more preferably an aliphatic
hydrocarbon chain having 2 or 3 carbon atoms.
##STR00003##
[0052] In general formula (III), t represents an integer of 1 to
100, and n2 represents an integer of 1 to 19. L.sup.3 represents an
(n2+1)-valent aliphatic hydrocarbon group having 1 to 20 carbon
atoms or an (n2+1)-valent aromatic hydrocarbon group having 6 to 20
carbon atoms, and L.sup.4 represents an aliphatic hydrocarbon chain
having 2 to 6 carbon atoms.
[0053] To provide an acoustic matching layer with further improved
breaking energy and further reduced variation in acoustic
characteristics, t is preferably an integer of 1 to 50, more
preferably an integer of 2 to 20.
[0054] n2 is preferably an integer of 2 to 19, more preferably an
integer of 2 to 5, still more preferably 3.
[0055] The above aliphatic hydrocarbon group represented by L.sup.3
is preferably an (n2+1)-valent aliphatic hydrocarbon group having 2
to 10 carbon atoms, more preferably an (n2+1)-valent aliphatic
hydrocarbon group having 2 to 6 carbon atoms, still more preferably
an (n2+1)-valent aliphatic hydrocarbon group having 2 to 4 carbon
atoms.
[0056] The above aromatic hydrocarbon group represented by L.sup.3
is preferably an (n2+1)-valent aromatic hydrocarbon group having 6
to 15 carbon atoms, more preferably an (n2+1)-valent aromatic
hydrocarbon group having 6 to 10 carbon atoms, still more
preferably (n2+1)-valent benzene.
[0057] L.sup.4 is more preferably an aliphatic hydrocarbon chain
having 2 to 4 carbon atoms, still more preferably an aliphatic
hydrocarbon chain having 2 or 3 carbon atoms.
##STR00004##
[0058] In general formula (IV), u represents an integer of 1 to
100, n3 and n4 each represent an integer of 1 or more, and the sum
of n3 and n4 is 20 or less. L.sup.5 represents an (n3+1)-valent
aliphatic hydrocarbon group having 1 to 20 carbon atoms or an
(n3+1)-valent aromatic hydrocarbon group having 6 to 20 carbon
atoms. L.sup.6 represents an (n4+1)-valent aliphatic hydrocarbon
group having 1 to 20 carbon atoms or an (n4+1)-valent aromatic
hydrocarbon group having 6 to 20 carbon atoms. L.sup.7 represents
an aliphatic hydrocarbon chain having 2 to 6 carbon atoms.
[0059] To provide an acoustic matching layer with further improved
breaking energy and further reduced variation in acoustic
characteristics, u is preferably an integer of 1 to 50, more
preferably an integer of 2 to 20.
[0060] n3 and n4 are each preferably an integer of 2 to 10, more
preferably an integer of 2 to 5, still more preferably 2 or 3.
[0061] The above aliphatic hydrocarbon group represented by L.sup.5
is preferably an (n3+1)-valent aliphatic hydrocarbon group having 2
to 15 carbon atoms, more preferably an (n3+1)-valent aliphatic
hydrocarbon group having 2 to 10 carbon atoms, still more
preferably an (n3+1)-valent aliphatic hydrocarbon group having 3 to
6 carbon atoms.
[0062] The above aromatic hydrocarbon group represented by L.sup.5
is preferably an (n3+1)-valent aromatic hydrocarbon group having 6
to 15 carbon atoms, more preferably an (n3+1)-valent aromatic
hydrocarbon group having 6 to 10 carbon atoms, still more
preferably (n3+1)-valent benzene.
[0063] The above aliphatic hydrocarbon group represented by L.sup.6
is preferably an (n4+1)-valent aliphatic hydrocarbon group having 2
to 15 carbon atoms, more preferably an (n4+1)-valent aliphatic
hydrocarbon group having 2 to 10 carbon atoms, still more
preferably an (n4+1)-valent aliphatic hydrocarbon group having 3 to
6 carbon atoms.
[0064] The above aromatic hydrocarbon group represented by L.sup.6
is preferably an (n4+1)-valent aromatic hydrocarbon group having 6
to 15 carbon atoms, more preferably an (n4+1)-valent aromatic
hydrocarbon group having 6 to 10 carbon atoms, still more
preferably (n4+1)-valent benzene.
[0065] L.sup.7 is more preferably an aliphatic hydrocarbon chain
having 2 to 4 carbon atoms, still more preferably an aliphatic
hydrocarbon chain having 2 or 3 carbon atoms.
[0066] The polyamine compound (B1) used in the present invention
may have one or more substituents T given below as long as the
effects of the present invention are not impaired.
[0067] Examples of substituents T include the following.
[0068] Examples include alkyl groups (preferably having 1 to 20
carbon atoms), alkenyl groups (preferably having 2 to 20 carbon
atoms), alkynyl groups (preferably having 2 to 20 carbon atoms),
cycloalkyl groups (preferably having 3 to 20 carbon atoms, alkyl
groups as used herein are generally meant to include cycloalkyl
groups), aryl groups (preferably having 6 to 26 carbon atoms),
aralkyl groups (preferably having 7 to 23 carbon atoms),
heterocyclic groups (preferably heterocyclic groups having 2 to 20
carbon atoms, preferably 5- or 6-membered heterocyclic groups
having at least one oxygen atom, sulfur atom, or nitrogen atom),
alkoxy groups (preferably having 1 to 20 carbon atoms), aryloxy
groups (preferably having 6 to 26 carbon atoms, alkoxy groups as
used herein are generally meant to include aryloxy groups),
alkoxycarbonyl groups (preferably having 2 to 20 carbon atoms),
aryloxycarbonyl groups (preferably having 6 to 26 carbon atoms),
amino groups (preferably amino groups having 0 to 20 carbon atoms,
including alkylamino groups and arylamino groups), sulfamoyl groups
(preferably having 0 to 20 carbon atoms), acyl groups (preferably
having 1 to 20 carbon atoms), aryloyl groups (preferably having 7
to 23 carbon atoms, acyl groups as used herein are generally meant
to include aryloyl groups), acyloxy groups (preferably having 1 to
20 carbon atoms), aryloyloxy groups (preferably having 7 to 23
carbon atoms, acyloxy groups as used herein are generally meant to
include aryloyloxy groups), carbamoyl groups (preferably having 1
to 20 carbon atoms), acylamino groups (preferably having 1 to 20
carbon atoms), alkylthio groups (preferably having 1 to 20 carbon
atoms), arylthio groups (preferably having 6 to 26 carbon atoms),
alkylsulfonyl groups (preferably having 1 to 20 carbon atoms),
arylsulfonyl groups (preferably having 6 to 22 carbon atoms),
alkylsilyl groups (preferably having 1 to 20 carbon atoms),
arylsilyl groups (preferably having 6 to 42 carbon atoms),
alkoxysilyl groups (preferably having 1 to 20 carbon atoms),
aryloxysilyl groups (preferably having 6 to 42 carbon atoms),
phosphoryl groups (preferably phosphoryl groups having 0 to 20
carbon atoms, for example, --OP(.dbd.O)(R.sup.P).sub.2), phosphonyl
groups (preferably phosphonyl groups having 0 to 20 carbon atoms,
for example, --P(.dbd.O)(R.sup.P).sub.2), phosphinyl groups
(preferably phosphinyl groups having 0 to 20 carbon atoms, for
example, --P(R.sup.P).sub.2), (meth)acryloyl groups,
(meth)acryloyloxy groups, (meth)acryloylimino groups
((meth)acrylamide groups), hydroxy groups, sulfanyl groups, carboxy
groups, phosphate groups, phosphonate groups, sulfonate groups,
cyano groups, and halogen atoms (e.g., fluorine, chlorine, bromine,
and iodine). R.sup.P is a hydrogen atom, a hydroxy group, or a
substituent (preferably a group selected from the group consisting
of substituents T).
[0069] Each of these groups listed as substituents T may be further
substituted with any of the above substituents T.
[0070] When a compound, a substituent, a linking group, or the like
includes, for example, an alkyl group, an alkylene group, an
alkenyl group, an alkenylene group, an alkynyl group, or an
alkynylene group, these groups may be cyclic or chain-like, may be
linear or branched, and may be substituted as described above or
unsubstituted.
[0071] Specific examples of the polyamine compound (B1) used in the
present invention include, but are not limited to, the
following.
##STR00005## ##STR00006## ##STR00007## ##STR00008## ##STR00009##
##STR00010##
[0072] The polyamine compound (B1) may be composed of a single
compound or a combination of two or more compounds. The polyamine
compound (B1) used in the present invention can be synthesized by a
usual method. Alternatively, a commercially available product may
be used.
[0073] To improve the heat resistance and productivity of an
acoustic matching layer, the composition according to the present
invention preferably includes a polyamine compound (B2) not having
an oxygen atom as a constituent atom.
[0074] The polyamine compound (B2) is not particularly limited
except for not having an oxygen atom as a constituent atom, and is
preferably a polyamine compound having an aromatic ring or an
alicyclic ring, more preferably a polyamine compound having an
alicyclic ring. The amino group in the polyamine compound (B2) is a
primary amino group or a secondary amino group, preferably a
primary amino group. The number of amino groups in the polyamine
compound (B2) may be any number more than one, and is preferably 2
to 5, more preferably 2 to 4, still more preferably 2 or 3, further
more preferably 2.
[0075] The polyamine compound (B2) having two primary amino groups
is preferably a polyamine compound represented by general formula
(V) below.
H.sub.2N-L.sup.8-NH.sub.2 General formula (V)
[0076] L.sup.8 represents a divalent linking group. The linking
group does not have an oxygen atom.
[0077] L.sup.8 is preferably an alkylene group, an arylene group,
an imino group, or a divalent linking group formed by combining
these groups.
[0078] The alkylene group may be linear or cyclic, or may be a
combination of a linear alkylene group and a cyclic alkylene group.
The number of carbon atoms in the alkylene group is preferably 1 to
30, more preferably 1 to 20. Specific examples of the alkylene
group include methylene, ethylene, hexamethylene,
2,4,4-trimethylhexamethylene, 2,2,4-trimethylhexamethylene,
2-methylpentamethylene, cyclohexylene, dodecamethylene, and groups
formed by combining at least two groups among them (preferably
groups formed by combining two to five groups, more preferably
groups formed by combining two to four groups, still more
preferably groups formed by combining two or three groups).
[0079] The number of carbon atoms in the arylene group is
preferably 6 to 14, more preferably 6 to 10, and specific examples
include phenylene and naphthylene.
[0080] Examples of the divalent linking group formed by combining
an alkylene group, an arylene group, or an imino group include
groups formed by combining an alkylene group and an imino group and
groups formed by combining an alkylene group and an arylene
group.
[0081] L.sup.8 is preferably a cyclic alkylene group, a group
formed by combining a linear alkylene group and a cyclic alkylene
group, an arylene group, or a group formed by combining a linear
alkylene group and an arylene group, more preferably a cyclic
alkylene group or a group formed by combining a linear alkylene
group and a cyclic alkylene group.
[0082] The molecular weight of the polyamine compound (B2) is
preferably 50 to 2000, more preferably 100 to 500.
[0083] Specific examples of the polyamine compound (B2) include
polyethyleneamines (e.g., ethylenediamine (EDA), diethylenetriamine
(DETA), triethylenetetramine (TETA), tetraethylenepentamine (TEPA),
pentaethylenehexamine (PEHA)), dipropylenetriamine,
polypropyleneamines (e.g., dipropylenetriamine), aminopropylated
ethylenediamines (e.g., N-(3-aminopropyl)ethylenediamine,
N,N'-bis(3-aminopropyl)ethylenediamine,
N,N,N'-tris(3-aminopropyl)ethylenediamine), aminopropylated
propylenediamines (e.g., N-(3-aminopropyl)propylenediamine,
N,N'-bis(3-aminopropyl)propylenediamine,
N,N,N'-tris(3-aminopropyl)propylenediamine), 1,6-hexanediamine
(HMDA), 1,12-dodecanediamine, 2,2,4-trimethyl-1,6-hexanediamine,
2,4,4-trimethyl-1,6-hexanediamine, tripropylenetetramine,
N,N'-bis(3-aminopropyl)-1,3-diaminopropane,
N,N,N'-tris(3-aminopropyl)-1,3-diaminopropane,
2-methyl-1,5-pentanediamine (2-methylpentamethylenediamine),
1,2-diaminocyclohexane, 1,3-diaminocyclohexane
(1,3-cyclohexanediamine), 1,4-diaminocyclohexane, hydrogenated
ortho-toluenediamine, hydrogenated meta-toluenediamine,
1,3-bis(aminomethyl)cyclohexane, isophoronediamine (IPDA,
5-amino-1,3,3-trimethylcyclohexanemethylamine), menthanediamine
(1,8-p-menthanediamine, MDA), norbomanediamine,
4,4'-diamino-3,3'-dimethyldicyclohexylmethane
(4,4'-methylenebis(2-methylcyclohexylamine),
bis(4-aminocyclohexyl)methane, 1,3-bis(aminocyclohexyl)propane,
1-cyclohexylamino-3-aminopropane, m-phenylenediamine,
4,4'-diaminodiphenylmethane (DDM, 4,4'-methylenedianiline),
4,4'-ethylenedianiline (4,4'-diaminobibenzyl,
4,4'-diamino-1,2-diphenylethane), tri(aminoethyl)benzene,
tri(aminobutyl)naphthalene, toluenediamine
(2-methyl-p-phenylenediamine), and diethyltoluenediamine.
[0084] Of these, 1,6-hexanediamine, 1,12-dodecanediamine,
2,2,4-trimethyl-1,6-hexanediamine,
2,4,4-trimethyl-1,6-hexanediamine, 1,3-diaminocyclohexane,
2-methyl-1,5-pentanediamine, m-phenylenediamine,
4,4'-ethylenedianiline,
4,4'-diamino-3,3'-dimethyldicyclohexylmethane, isophoronediamine,
and menthanediamine are preferred, and isophoronediamine and
menthanediamine are more preferred.
[0085] The polyamine compound (B2) may be composed of a single
compound or a combination of two or more compounds. The polyamine
compound (B2) used in the present invention can be synthesized by a
usual method. Alternatively, a commercially available product may
be used.
[0086] In addition to the polyamine compounds (B1) and (B2), the
composition according to the present invention may include another
amine compound (e.g., a tertiary amine compound) as long as the
effects of the present invention are not impaired. The total
content of the polyamine compounds (B1) and (B2) in the polyamine
compounds contained in the composition according to the present
invention is preferably 80 mass % or more, more preferably 90 mass
% or more, still more preferably 95 mass % or more.
[0087] In the composition according to the present invention,
curing reaction of the epoxy resin (A) may proceed over time.
Accordingly, the properties of the composition may change over
time, thus being unstable. However, for example, if the composition
is preserved at a temperature of -10.degree. C. or lower, the
composition can be brought into a state in which each component is
stably maintained with no curing reaction occurring or with curing
reaction sufficiently inhibited.
[0088] It is also preferred that a resin composition including the
epoxy resin (A) and the metal particles (C) be used as a base resin
and that the base resin and a curing agent including the polyamine
compound (B1) be used in the form of an acoustic matching layer
material set in which the base resin and the curing agent are
separate from each other. In forming an acoustic matching layer,
the base resin and the curing agent are mixed together to prepare
the composition according to the present invention, and a layer is
formed using the composition, whereby the acoustic matching layer
can be formed. The curing agent preferably includes the polyamine
compound (B2).
[0089] In the composition according to the present invention, the
equivalent ratio of the polyamine compound (B1) to the epoxy resin
(A) may be, for example, polyamine compound (B1)/epoxy resin (A)
(moles of amino groups.times.2 (moles of active hydrogen)/moles of
epoxy groups)=0.5/1 to 1/0.5.
[0090] When the composition according to the present invention is
prepared by using the above acoustic matching layer material set
and mixing the base resin and the curing agent together in forming
a layer, the base resin and the curing agent are preferably mixed
together such that the mass ratio of the polyamine compound (B1) to
the epoxy resin (A) is 1/99 to 80/20, more preferably 10/90 to
60/40.
[0091] In the composition according to the present invention, the
equivalent ratio of the polyamine compound (B2) to the epoxy resin
(A) may be, for example, polyamine compound (B2)/epoxy resin (A)
(moles of active hydrogen of amino groups/moles of epoxy groups)
0.9, preferably .ltoreq.0.50 from the viewpoint of
productivity.
Metal Particles (C)
[0092] The composition according to the present invention contains
the metal particles (C). By adjusting the content of the metal
particles (C), the density of the composition can be adjusted, and
the acoustic impedance of an acoustic matching layer to be obtained
can be adjusted to a desired level. The metal particles (C) may be
surface treated.
[0093] The surface treatment of the metal particles may be
performed by any method, and commonly used surface treatment
techniques may be used. Examples of treatment methods include oil
treatments with hydrocarbon oil, ester oil, lanolin, and the like,
silicone treatments with dimethylpolysiloxane,
methylhydrogenpolysiloxane, methylphenylpolysiloxane, and the like,
fluorine compound treatments with perfluoroalkyl group-containing
esters, perfluoroalkylsilanes, perfluoropolyethers, perfluoroalkyl
group-containing polymers, and the like, silane coupling agent
treatments with 3-methacryloxypropyltrimethoxysilane,
3-glycidoxypropyltrimethoxysilane, and the like, titanate coupling
agent treatments with isopropyltriisostearoyl titanate,
isopropyltris(dioctylpyrophosphate) titanate, and the like,
metallic soap treatments, amino acid treatments with acylglutamic
acid and the like, lecithin treatments with hydrogenated egg yolk
lecithin and the like, collagen treatments, polyethylene
treatments, moisturizing treatments, inorganic compound treatments,
and mechanochemical treatments.
[0094] There is no particular limitation on a metal constituting
the metal particles (C). The metal may be a metal atom alone, a
metal carbide, a metal nitride, a metal oxide, a metal boride, or
an alloy. Examples of alloys include high-tensile steel (Fe--C),
chromium molybdenum steel (Fe--Cr--Mo), manganese molybdenum steel
(Fe--Mn-Mo), stainless steel (Fe--Ni--Cr), 42 alloys, Invar
(Fe--Ni), permendur (Fe--Co), silicon steel (Fe--Si), red brass,
tombac (Cu--Zn), German silver (Cu--Zn--Ni), bronze (Cu--Sn),
cupronickel (Cu--Ni), shakudo (Cu--Au), constantan (Cu--Ni),
duralumin (Al--Cu), Hastelloy (Ni--Mo--Cr--Fe), Monel (Ni--Cu),
Inconel (Ni--Cr--Fe), nichrome (Ni--Cr), ferromanganese (Mn--Fe),
and cemented carbide (WC/Co).
[0095] From the viewpoint of general versatility and the ease of
surface modification, the metal atom constituting the metal
particles (C) preferably includes at least one metal atom in groups
4 to 12 of the periodic table.
[0096] More preferably, the metal atom includes at least one of Zn,
Au, Ag, Zr, W, Ta, Fe, Cu, Ni, Pt, or Mo.
[0097] From the viewpoint of dispersion stability and acoustic
stability, the particle size of the metal particles (C) used in the
present invention is preferably 0.01 to 100 .mu.m, more preferably
1 to 10 .mu.m. As used herein, the "particle size" of the metal
particles (C) means an average primary particle size.
[0098] As used herein, the average primary particle size means a
volume average particle size. The volume average particle size is
determined as described below.
[0099] The metal particles (C) are added to methanol at a
concentration of 0.5 mass %, and the mixture is sonicated for 10
minutes to disperse the metal particles (C). The particle size
distribution of the metal particles (C) thus treated is measured
using a laser diffraction/scattering particle size distribution
analyzer (manufactured by Horiba, Ltd., trade name: LA950V2), and
the measured volumetric median diameter is used as the volume
average particle size. The median diameter corresponds to a
particle size at 50% in the particle size distribution represented
in cumulative form.
[0100] In the composition according to the present invention, the
contents of the metal particles (C), the epoxy resin (A), and the
polyamine compound (B1) are each appropriately adjusted depending
on, for example, the desired acoustic impedance. For example, when
the acoustic matching layer is formed of multiple layers, the
content of the metal particles (C) in the composition used for the
acoustic matching layer on the piezoelectric element side can be
relatively high, and the content of the metal particles (C) in the
composition used for the acoustic matching layer on the acoustic
lens side can be relatively low. This can provide a gradient in
acoustic impedance from the piezoelectric element side toward the
acoustic lens side, thus further increasing the efficiency of
propagation of acoustic waves.
[0101] The composition according to the present invention may be
composed of the epoxy resin (A), the polyamine compound (B1), the
metal particles (C), and optionally the polyamine compound (B2).
The composition may also contain other component as long as the
effects of the present invention are not impaired. As the component
other than epoxy resin (A), the polyamine compound (B1), the metal
particles (C), and the polyamine compound (B2), for example, a
curing retarder, a solvent, a dispersant, a pigment, a dye, an
antistatic agent, an antioxidant, a flame retardant, or a thermal
conductivity improver can be appropriately added.
[0102] In the composition according to the present invention, the
sum of the contents of the epoxy resin (A), the polyamine compound
(B1), and the metal particles (C) is preferably 80 mass % or more,
more preferably 90 mass % or more. In the composition according to
the present invention, the sum of the contents of the epoxy resin
(A), the polyamine compound (B1), the metal particles (C), and the
polyamine compound (B2) is preferably 80 mass % or more, more
preferably 90 mass % or more, still more preferably 95 mass % or
more. Preparation of resin composition for acoustic matching
layer
[0103] The resin composition for an acoustic matching layer
according to the present invention can be obtained, for example, by
kneading the components of the resin composition for an acoustic
matching layer with a kneader, a pressure kneader, a Banbury mixer
(continuous kneader), a two-roll kneading apparatus, or the like.
This can provide a resin composition for an acoustic matching
layer, the resin composition including an epoxy resin (A), a
polyamine compound (B1), and metal particles (C) dispersed therein,
preferably an epoxy resin (A), a polyamine compound (B1), a
polyamine compound (B2), and metal particles (C) dispersed
therein.
[0104] When an acoustic matching layer material set that includes a
base resin made of a resin composition including an epoxy resin (A)
and metal particles (C) and includes a curing agent including a
polyamine compound (B1) is provided, the base resin can be obtained
by kneading the epoxy resin (A) and the metal particles (C). The
curing agent preferably includes a polyamine compound (B2). When an
acoustic matching layer is produced, the base resin and the curing
agent are mixed together to obtain the composition according to the
present invention. The composition is cured while being shaped,
whereby the acoustic matching layer or a precursor sheet thereof
can be formed.
[0105] The kneading and shaping are preferably performed while
removing bubbles, and thus usually performed under reduced
pressure.
Acoustic Matching Sheet (Acoustic Matching Layer)
[0106] By forming the composition according to the present
invention into a sheet shape and optionally, for example, cutting
or dicing the sheet to a desired thickness or shape, an acoustic
matching sheet can be obtained. The acoustic matching sheet is used
as an acoustic matching layer of an acoustic probe. The
configuration of an acoustic probe including an acoustic matching
layer will be described later.
[0107] In producing the sheet, the composition is formed into a
desired sheet shape at a low temperature at which no curing
reaction occurs or curing proceeds slowly, and then the shaped
product is cured, for example, by heating if necessary, to provide
an acoustic matching sheet or a precursor sheet thereof. That is,
the acoustic matching sheet according to the present invention is a
cured product having a three-dimensional network structure formed
by curing the composition according to the present invention.
Acoustic Probe
[0108] An acoustic probe according to the present invention has, as
an acoustic matching layer, an acoustic matching sheet formed by
using the composition according to the present invention.
[0109] An exemplary configuration of the acoustic probe according
to the present invention is shown in FIG. 1. The acoustic probe
shown in FIG. 1 is an ultrasound probe of an ultrasound diagnostic
apparatus. An ultrasound probe uses, particularly, ultrasonic waves
as acoustic waves for an acoustic probe. Thus, the basic structure
of an ultrasound probe can be applied to an acoustic probe without
any change.
Ultrasound Probe
[0110] An ultrasound probe 10, which is a main component part of an
ultrasound diagnostic apparatus, has a function to generate
ultrasonic waves as well as to transmit and receive ultrasonic
beams. The ultrasound probe 10 has a configuration in which an
acoustic lens 1, an acoustic matching layer 2, a piezoelectric
element layer 3, and a backing member 4 are disposed in this order
from a distal end (a surface to be in contact with a living body,
or a subject) portion, as shown in FIG. 1. In recent years,
ultrasound probes have also been proposed in which, for the purpose
of receiving a high-order harmonic, a transmitting ultrasonic
transducer (piezoelectric element) and a receiving ultrasonic
transducer (piezoelectric element) are made of different materials
to form a multilayer structure.
Piezoelectric Element Layer
[0111] The piezoelectric element layer 3 is a portion that
generates ultrasonic waves, and electrodes are affixed to opposite
sides of a piezoelectric element. When a voltage is applied, the
piezoelectric element oscillates by repeating expansion and
contraction to thereby generate ultrasonic waves.
[0112] As materials constituting piezoelectric elements, what is
called ceramic inorganic piezoelectric bodies, which are obtained
by polarizing single crystals of quartz, LiNbO.sub.3, LiTaO.sub.3,
KNbO.sub.3, and the like, thin films of ZnO, AlN, and the like, and
PbO.sub.3 (ZrO.sub.3, TiO.sub.3) sintered bodies, are widely used.
In general, piezoelectric ceramics with high conversion efficiency,
such as lead zirconate titanate (PZT), are used.
[0113] A piezoelectric element for detecting received waves on the
high-frequency side is required to have sensitivity over a wider
bandwidth. Thus, as a piezoelectric element suitable for a high
frequency and a wide band, an organic piezoelectric body obtained
using an organic macromolecular substance such as polyvinylidene
fluoride (PVDF) is used.
[0114] Furthermore, for example, JP2011-071842A discloses a
capacitive micromachined ultrasonic transducer (cMUT) that exhibits
excellent short-pulse characteristics and wideband characteristics,
is suitable for mass production, provides an array structure with
little variation in characteristics, and is obtained by using micro
electro mechanical systems (MEMS).
[0115] In the present invention, any of the piezoelectric element
materials can be preferably used.
Backing Member
[0116] The backing member 4, which is disposed in the back of the
piezoelectric element layer 3, suppresses an excessive oscillation
to shorten the pulse width of ultrasonic waves, thus contributing
to improving the axial resolution in an ultrasound diagnostic
image. Acoustic matching layer
[0117] The acoustic matching layer 2 is disposed in order to
achieve efficient transmission and reception of ultrasonic waves by
reducing the difference in acoustic impedance between the
piezoelectric element layer 3 and a subject.
Acoustic Lens
[0118] The acoustic lens 1 is disposed in order to converge
ultrasonic waves in a slice direction by utilizing refraction to
improve resolving power. The acoustic lens 1 comes into close
contact with a living body, or a subject, and is required to match
ultrasonic waves to the acoustic impedance of the living body (in
the case of a human body, 1.4 to 1.7.times.10.sup.6
kg/m.sup.2/sec), and the amount of ultrasonic wave attenuation in
the acoustic lens 1 itself is required to be small.
[0119] That is, by using, as a material for the acoustic lens 1,
such a material that the sound velocity in the material is
sufficiently lower than the sound velocity in a human body and that
causes less ultrasonic wave attenuation and has an acoustic
impedance value close to that of human body skin, the sensitivity
to transmit and receive ultrasonic waves are increased.
[0120] The operation of the ultrasound probe 10 having such a
configuration will be described. A voltage is applied to the
electrodes disposed on the opposite sides of the piezoelectric
element to resonate the piezoelectric element layer 3, thus
transmitting an ultrasonic signal from the acoustic lens to a
subject. At the time of reception, the piezoelectric element layer
3 is oscillated by a reflected signal (echo signal) from the
subject, and the oscillation is electrically converted into a
signal to obtain an image.
Method for Producing Acoustic Probe
[0121] The acoustic probe according to the present invention can be
produced by a usual method provided that the resin composition for
an acoustic matching layer according to the present invention is
used. That is, a method for producing an acoustic probe according
to the present invention includes forming an acoustic matching
layer on a piezoelectric element by using the resin composition for
an acoustic matching layer according to the present invention. The
piezoelectric element can be provided on a backing member by a
usual method.
[0122] Furthermore, an acoustic lens is formed on the acoustic
matching layer by a usual method using a material for forming the
acoustic lens.
Acoustic Measuring Apparatus
[0123] An acoustic measuring apparatus according to the present
invention has the acoustic probe according to the present
invention. The acoustic measuring apparatus has functions, for
example, to display the signal strength of a signal received by the
acoustic probe and to translate the signal into an image.
[0124] The acoustic measuring apparatus according to the present
invention may be an ultrasonic measuring apparatus including an
ultrasound probe.
EXAMPLES
[0125] The present invention will now be described in more detail
with reference to examples in which ultrasonic waves are used as
acoustic waves. It should be noted that in the present invention,
not only ultrasonic waves but also any acoustic waves of audio
frequencies may be used as long as appropriate frequencies are
selected according to the subject, the measurement conditions, and
so on. In the following examples, room temperature means 25.degree.
C.
Preparation of Resin Composition for Acoustic Matching Layer
(Example 1)
[0126] One hundred parts by mass of metal particles (iron powder
(Fe) (EW-I (trade name) manufactured by BASF) and 15 parts by mass
of an epoxy resin (A-1) (bisphenol A diglycidyl ether ("jER825"
(trade name) manufactured by Mitsubishi Chemical Corporation, epoxy
equivalent weight: 170)) serving as a base resin were stirred for 4
minutes at 1800 rpm under a reduced pressure of 1.0 Pa at room
temperature using a "THINKY MIXER ARV-310 (trade name, manufactured
by THINKY CORPORATION)" while being defoamed. Thereafter, the
resultant and 8 parts by mass of a polyamine compound (B-1)
(polyoxyalkylene diamine D230 (trade name, manufactured by Mitsui
Fine Chemicals, Inc., active hydrogen equivalent weight: 73)
serving as a curing agent were stirred for 4 minutes at 1800 rpm
under a reduced pressure of 1.0 Pa at room temperature using a
"THINKY MIXER ARV-310 (trade name, manufactured by THINKY
CORPORATION)" while being defoamed to prepare a resin composition
for an acoustic matching layer (Example 1).
[0127] Resin compositions for acoustic matching layers of Examples
other than Example 1 shown in Table 1 below were prepared in the
same manner as the preparation of the resin composition for an
acoustic matching layer of Example 1 except that compositions shown
in Table 1 below were used.
[0128] The obtained resin compositions for acoustic matching layers
were cured to produce sheets, and their breaking energy was
measured. Acoustic impedances at five points in each sheet were
measured, and their standard deviation was determined to evaluate
variation in acoustic characteristics. A productivity test was
performed using the resin compositions for acoustic matching
layers, and a heat resistance test was performed using the sheets
formed by curing the resin compositions for acoustic matching
layers. Details of the tests will be described below.
Breaking Energy
[0129] The resin compositions for acoustic matching layers were
each poured into a mold 5 cm long, 5 cm wide, and 0.4 mm high, and
cured at 80.degree. C. for 18 hours, then at 150.degree. C. for 1
hour to produce sheets. The sheets were each punched to a length of
4 cm and a width of 5 mm to prepare tensile test specimens.
[0130] Using a tensile tester (Autograph AGS-X/20N) (trade name,
manufactured by Shimadzu Corporation), the specimens were each
stretched symmetrically in the longitudinal direction at a tensile
speed of 30 mm/min to measure breaking energy. The criteria for
evaluation are given below. In this test, A and B are
acceptable.
Evaluation Criteria
[0131] A: 50 J or more
[0132] B: 45 J or more and less than 50 J
[0133] C: 40 J or more and less than 45 J
[0134] D: Less than 40 J
Variation in Acoustic Impedance (AI)
[0135] The resin compositions for acoustic matching layers were
each poured into a mold 5 cm long, 5 cm wide, and 2 mm high and
cured at 80.degree. C. for 18 hours, then at 150.degree. C. for 1
hour to produce sheets. For five points, neighborhoods of four
corners and the central part, of each sheet, acoustic impedances
were each calculated from a product of a density and a sound
velocity (density.times.sound velocity). The standard deviation of
the acoustic impedances at the five points was determined, and the
variation in acoustic characteristics was evaluated according to
the following evaluation criteria.
Sound Velocity
[0136] The ultrasonic velocity was measured at 25.degree. C. using
a sing-around ultrasonic velocity measuring instrument
(manufactured by Ultrasonic Engineering Co., Ltd., trade name
"Model UVM-2") in accordance with JIS Z2353 (2003). At each of the
five measurement sites, the whole inside of a circle with a
diameter of 1.5 cm (a size of a single-channel small probe) was
used as a measuring object.
Density
[0137] Densities at the five measurement sites at 25.degree. C.
were measured in accordance with a density measuring method of the
A method (water displacement method) described in JIS K7112 (1999)
by using an electronic densimeter (manufactured by Alfa Mirage Co.,
Ltd., trade name "SD-200L"). The density at each measurement site
is defined as a density of a sheet specimen (10 mm.times.10 mm
square) cut out from inside the above sound velocity measurement
site (the circle with a diameter of 1.5 cm). The criteria for
evaluation are given below. In this test, A and B are
acceptable.
Evaluation Criteria
[0138] A: Less than 0.5
[0139] B: 0.5 or more and less than 0.7
[0140] C: 0.7 or more and less than 0.9
[0141] D: 0.9 or more
Productivity
[0142] Productivity was evaluated by determining the rate of cure
of the resin compositions for acoustic matching layers on the basis
of tackiness of the resin compositions for acoustic matching
layers. The tackiness was determined by curing each resin
composition for an acoustic matching layer in a thermostat chamber
at 60.degree. C. for a predetermined period of time and touching
the surface of the resin composition for an acoustic matching layer
to check if there was adhesion of the resin composition. The time
until there was no adhesion of the resin composition for an
acoustic matching layer (the time until the resin composition for
an acoustic matching layer cured) was measured to thereby evaluate
productivity.
Evaluation Criteria
[0143] A: 10 minutes or more and less than 20 minutes B: 5 minutes
or more and less than 10 minutes C: 20 minutes or more and less
than 30 minutes D: 30 minutes or more E: Less than 5 minutes
[0144] From the viewpoint of productivity, an excessively short
curing time is disadvantageous because curing is completed before
the next step, and an excessively long curing time is also
disadvantageous because it takes time. In this test, a curing time
of 10 minutes or more and less than 20 minutes was defined to be
optimal, and whether the productivity was high or low was evaluated
as follows.
Productivity: A>B>C>D>E
Heat Resistance
[0145] Heat resistance was evaluated by using a glass transition
temperature (Tg) of each cured product (the sheet obtained by
curing each resin composition for an acoustic matching layer). The
glass transition temperature (Tg) of each cured product was defined
as a temperature at which the cured product exhibits a maximum
value of tan .delta. in a dynamic viscoelastic measurement. The
dynamic viscoelastic measurement was performed at a frequency of 1
Hz using a viscoelastometer (trade name: DMS6100) manufactured by
Seiko Instruments Inc. The value of Tg was classified by the
following evaluation criteria to evaluate heat resistance.
Evaluation Criteria
[0146] A: 140.degree. C. or higher B: 120.degree. C. or higher and
lower than 140.degree. C. C: 100.degree. C. or higher and lower
than 120.degree. C. D: 80.degree. C. or higher and lower than
100.degree. C. E: Lower than 80.degree. C.
TABLE-US-00001 TABLE 1 Epoxy resin Polyamine compound Polyamine
compound Metal particles (A) (B1) (B2) (C) Parts Parts Parts Parts
Heat by by Equivalent by Equivalent by Specific Breaking Variation
Produc- resis- Type mass Type mass ratio (1) Type mass ratio (2)
Type mass gravity energy in AI tivity tance Example 1 A-1 15 B1-1 5
1 -- -- -- Fe 100 3.4 A A C D Example 2 A-1 15 B1-6 4 1 -- -- -- Fe
100 3.4 B A C E Example 3 A-1 15 B1-11 9 1 -- -- -- Fe 100 3.3 A B
D D Example 4 A-1 15 B1-15 10 1 -- -- -- Fe 100 3.3 A A D D Example
5 A-1 15 B1-19 8 1 -- -- -- Fe 100 3.3 B A C D Example 6 A-1 15
B1-23 4 1 -- -- -- Fe 100 3.4 A B D D Example 7 A-1 15 B1-24 4 1 --
-- -- Fe 100 3.4 A B C E Example 8 A-1 15 B1-25 4 1 -- -- -- Fe 100
3.4 A B D C Example 9 A-1 15 B1-26 4 1 -- -- -- Fe 100 3.4 B B C C
Example 10 A-1 15 B1-27 8 1 -- -- -- Fe 100 3.3 A B D D Example 11
A-1 15 B1-30 7 1 -- -- -- Fe 100 3.3 A B C D Example 12 A-1 15
B1-33 7 1 -- -- -- Fe 100 3.3 A B D D Example 13 A-1 15 B1-35 6 1
-- -- -- Fe 100 3.3 A B C D Example 14 A-1 15 B1-37 7 1 -- -- -- Fe
100 3.3 A B D D Example 15 A-1 15 B1-39 6 1 -- -- -- Fe 100 3.3 A B
C D Example 16 A-1 15 B1-41 7 1 -- -- -- Fe 100 3.3 A B D D Example
17 A-1 15 B1-43 6 1 -- -- -- Fe 100 3.3 A B C D Example 18 A-1 6
B1-16 17 1 -- -- -- Fe 100 3.3 A A D E Example 19 A-1 3 B1-17 20 1
-- -- -- Fe 100 3.3 A A D E Example 20 A-1 1 B1-18 22 1 -- -- -- Fe
100 3.3 B B D E Example 21 A-2 15 B1-15 9 1 -- -- -- Fe 100 3.3 B A
D D Example 22 A-3 15 B1-15 7 1 -- -- -- Fe 100 3.3 B A D D Example
23 A-4 15 B1-15 10 1 -- -- -- Fe 100 3.2 A A D D Example 24 A-5 15
B1-15 10 1 -- -- -- Fe 100 3.2 A A D D Example 25 A-6 15 B1-15 7 1
-- -- -- Fe 100 3.3 B A D D Example 26 A-7 11 B1-15 12 1 -- -- --
Fe 100 3.3 A A D D Example 27 A-1 15 B1-15 10 1 -- -- -- Zn 100 3.2
A A D D Example 28 A-1 12 B1-15 8 1 -- -- -- Au 100 3.6 A A D D
Example 29 A-1 13 B1-15 8 1 -- -- -- Ag 100 3.4 A A D D Example 30
A-1 15 B1-15 10 1 -- -- -- Zr 100 3.2 A A D D Example 31 A-1 12
B1-15 8 1 -- -- -- Ta 100 3.5 A A D D
TABLE-US-00002 TABLE 2 Epoxy resin Polyamine compound Polyamine
compound Metal particles (A) (B1) (B2) (C) Parts Parts Parts Parts
Heat by by Equivalent by Equivalent by Specific Breaking Variation
Produc- resis- Type mass Type mass ratio (1) Type mass ratio (2)
Type mass gravity energy in AI tivity tance Example 32 A-1 15 B1-15
10 1 -- -- -- Cu 100 3.3 A A D D Example 33 A-1 15 B1-15 10 1 -- --
-- Ni 100 3.3 A A D D Example 34 A-1 12 B1-15 8 1 -- -- -- Pt 100
3.7 A A D D Example 35 A-1 15 B1-15 10 1 -- -- -- Mo 100 3.4 A A D
D Example 36 A-1 15 B1-15 3 0.2 -- -- -- Fe 100 3.4 B A D D Example
37 A-1 15 B1-15 5 0.5 -- -- -- Fe 100 3.4 A A D D Example 38 A-1 15
B1-15 15 1.5 -- -- -- Fe 100 3.2 A A D D Example 39 A-1 15 B1-15 22
2.1 -- -- -- Fe 100 3.2 B A D D Example 40 A-1 8 B1-15 4 0.8 -- --
-- Fe 100 5.1 A A D D Example 41 A-1 30 B1-15 15 0.8 -- -- -- Fe
100 2.9 A A D D Example 42 A-1 45 B1-15 22 0.8 -- -- -- Fe 100 2.4
A A D D Example 43 A-1 60 B1-15 30 0.8 -- -- -- Fe 100 2.2 A A D D
Example 44 A-4 8 B1-15 4 0.8 -- -- -- Fe 100 5.1 A A D D Example 45
A-4 30 B1-15 15 0.8 -- -- -- Fe 100 2.9 A A D D Example 46 A-4 45
B1-15 22 0.8 -- -- -- Fe 100 2.4 A A D D Example 47 A-4 60 B1-15 30
0.8 -- -- -- Fe 100 2.2 B A D D Example 48 A-1 15 B1-15 8 0.8 B2-3
2 0.2 Fe 100 3.3 B A A B Example 49 A-1 15 B1-15 6 0.5 B2-3 4 0.5
Fe 100 3.3 A A A B Example 50 A-1 15 B1-15 3 0.2 B2-3 7 0.8 Fe 100
3.3 A A B A Example 51 A-1 15 B1-15 8 0.8 B2-6 2 0.2 Fe 100 3.3 B A
A B Example 52 A-1 15 B1-15 6 0.5 B2-6 4 0.5 Fe 100 3.3 A A A B
Example 53 A-1 15 B1-15 3 0.2 B2-6 7 0.8 Fe 100 3.3 A A B A Example
54 A-1 15 B1-15 8 0.8 B2-8 2 0.2 Fe 100 3.3 A A A B Example 55 A-1
15 B1-15 6 0.5 B2-8 4 0.5 Fe 100 3.3 A A A A Example 56 A-1 15
B1-15 3 0.2 B2-8 7 0.8 Fe 100 3.3 A A B A Example 57 A-1 15 B1-15 8
0.8 B2-9 2 0.2 Fe 100 3.4 A A A B Example 58 A-1 15 B1-15 6 0.5
B2-9 4 0.5 Fe 100 3.4 A A A A Example 59 A-1 15 B1-15 3 0.2 B2-9 7
0.8 Fe 100 3.4 A A B A Example 60 A-1 15 B1-15 8 0.8 B2-10 2 0.2 Fe
100 3.4 A A A B Example 61 A-1 15 B1-15 6 0.5 B2-10 4 0.5 Fe 100
3.4 A A A A Example 62 A-1 15 B1-15 3 0.2 B2-10 7 0.8 Fe 100 3.4 A
A B A
TABLE-US-00003 TABLE 3 Epoxy resin Polyamine compound Polyamine
compound Metal particles (A) (B1) (B2) (C) Parts Parts Parts Parts
Heat by by Equivalent by Equivalent by Specific Breaking Variation
Produc- resis- Type mass Type mass ratio (1) Type mass ratio (2)
Type mass gravity energy in AI tivity tance Comparative A-1 15 --
-- -- B2-1 3 1 Fe 100 3.3 C D E D Example 1 Comparative A-1 15 --
-- -- B2-2 4 1 Fe 100 3.3 C C E D Example 2 Comparative A-1 15 --
-- -- B2-3 4 1 Fe 100 3.3 C C E D Example 3 Comparative A-1 15 --
-- -- B2-4 3 1 Fe 100 3.3 D D E C Example 4 Comparative A-1 15 --
-- -- B2-5 3 1 Fe 100 3.3 D D E D Example 5 Comparative A-1 15 --
-- -- B2-6 2 1 Fe 100 3.3 D D D C Example 6 Comparative A-1 15 --
-- -- B2-7 5 1 Fe 100 3.3 C C E C Example 7 Comparative A-1 15 --
-- -- B2-8 5 1 Fe 100 3.3 C B E C Example 8 Comparative A-1 15 --
-- -- B2-9 4 1 Fe 100 3.3 C B E C Example 9 Comparative A-1 15 --
-- -- B2-10 4 1 Fe 100 3.3 C B E C Example 10
NOTES OF TABLES
[0147] "-" means, for example, not containing the corresponding
component.
Equivalent ratio (1): polyamine compound (B1)/epoxy resin (A)
Equivalent ratio (2): polyamine compound (B2)/epoxy resin (A)
Epoxy Compound (A)
[0148] (A-1) Bisphenol A diglycidyl ether ("jER825" (trade name)
manufactured by Mitsubishi Chemical Corporation, epoxy equivalent
weight: 170) (A-2) Bisphenol A diglycidyl ether ("jER828" (trade
name) manufactured by Mitsubishi Chemical Corporation, epoxy
equivalent weight: 190) (A-3) Bisphenol A diglycidyl ether
("jER834" (trade name) manufactured by Mitsubishi Chemical
Corporation, epoxy equivalent weight: 230) (A-4) Bisphenol F
diglycidyl ether ("EPICLON830" (trade name) manufactured by DIC
Corporation, epoxy equivalent weight: 170) (A-5) Epoxy novolac
resin (manufactured by Sigma-Aldrich, product number 406775, epoxy
equivalent weight: 170) (A-6) Bisphenol A propoxylate diglycidyl
ether (manufactured by Sigma-Aldrich, epoxy equivalent weight: 228)
(A-7) 4,4'-Methylenebis(N,N-diglycidylaniline) (manufactured by
Tokyo Chemical Industry Co., Ltd., epoxy equivalent weight:
106)
Polyamine Compound (B1)
[0149] Polyamine compounds used in EXAMPLES are exemplary compounds
listed above.
Polyamine Compound (B2)
[0150] B2-1: 1,6-Hexanediamine (manufactured by Tokyo Chemical
Industry Co., Ltd., active hydrogen equivalent weight: 29) B2-2:
1,12-Dodecanediamine (manufactured by Tokyo Chemical Industry Co.,
Ltd., active hydrogen equivalent weight: 50) B2-3:
Trimethylhexamethylenediamine (manufactured by Tokyo Chemical
Industry Co., Ltd., mixture of 2,2,4-trimethyl-1,6-hexanediamine
and 2,4,4-trimethyl-1,6-hexanediamine, active hydrogen equivalent
weight: 40) B2-4: 1,3-Cyclohexanediamine (manufactured by Tokyo
Chemical Industry Co., Ltd., active hydrogen equivalent weight: 29)
B2-5: 2-Methylpentamethylenediamine (manufactured by Tokyo Chemical
Industry Co., Ltd., active hydrogen equivalent weight: 29) B2-6:
m-Phenylenediamine (manufactured by Tokyo Chemical Industry Co.,
Ltd., active hydrogen equivalent weight: 27) B2-7:
4,4'-Ethylenedianiline (manufactured by Tokyo Chemical Industry
Co., Ltd., active hydrogen equivalent weight: 53) B2-8:
4,4'-Methylenebis(2-methylcyclohexylamine) (manufactured by Tokyo
Chemical Industry Co., Ltd., active hydrogen equivalent weight: 59)
B2-9: 5-Amino-1,3,3-trimethylcyclohexanemethylamine (manufactured
by FUJIFILM Wako Pure Chemical Corporation, active hydrogen
equivalent weight: 43) B2-10: 1,8-p-Menthanediamine (manufactured
by Aldrich, active hydrogen equivalent weight: 43)
Metal Particles (C)
[0151] Fe: Iron powder (EW-I (trade name) manufactured by BASF,
average particle size: 2 .mu.m)
Zn: Zinc powder (average particle size: 3 .mu.m) Au: Gold powder
(average particle size: 1 .mu.m) Ag: Silver powder (average
particle size: 1 .mu.m) Zr: Zirconia powder (average particle size:
2 .mu.m) Ta: Tantalum powder (average particle size: 3 .mu.m) Cu:
Copper powder (average particle size: 3 .mu.m) Ni: Nickel powder
(average particle size: 2 .mu.m) Pt: Platinum powder (average
particle size: 1 .mu.m) Mo: Molybdenum powder (Mo-3 manufactured by
Japan New Metals Co., Ltd., average particle size: 3 .mu.m)
[0152] Metal powders without company names were prepared by
pulverization in our company.
[0153] As shown in Table 1 above, sheets formed by using
compositions prepared by combining an epoxy resin (A), metal
particles (C), and a diamine compound not satisfying the
requirements of the present invention had poor mechanical strength
and great variation in intrasheet acoustic characteristics
(Comparative Examples 1 to 7).
[0154] By contrast, sheets formed by using compositions prepared by
combining an epoxy resin (A), metal particles (C), and a polyamine
compound (B1) had high mechanical strength and little variation in
intrasheet acoustic characteristics (Examples 1 to 62).
[0155] While the present invention has been described in connection
with embodiments thereof, we do not intend to limit our invention
in any detail of the description unless otherwise specified.
Rather, the invention should be broadly construed without departing
from the spirit and scope of the invention as defined by the
appended claims.
REFERENCE SIGNS LIST
[0156] 1 acoustic lens [0157] 2 acoustic matching layer [0158] 3
piezoelectric element layer [0159] 4 backing member [0160] 7
housing [0161] 9 cord [0162] 10 ultrasound search unit (probe)
* * * * *